Despite the impressive abilities of people to sense, remember, and reason about the world, cognitive abilities are extremely limited in well-characterized ways. In particular, psychologists have found that people wrestle with scarce attentional resources and limited working memory. Such limitations become salient when people are challenged with remembering more than a handful of new ideas or items in the short term, recognizing important targets against a background pattern of items, or interleaving multiple tasks.
These results indicate that people must typically inspect the world through a limited spotlight of attention. As such, most people often generate clues implicitly and explicitly about what they are selectively attending to and how deeply they are focusing. Findings about limited attentional resources have significant implications for how computational systems and interfaces are designed. With respect to attentional resources, electronic communications are usually transmitted in a one-directional manner, wherein the receiver or recipient of a message is notified upon message delivery irregardless of the recipient's ability to process the communications. Thus, with instant messaging as one example, receivers of an instant message are provided with a pop-up window indicating a sender's desire to communicate. This type of interruption however, does not consider the recipient's availability to receive such messages or engage in current conversation.